SCADAmetrics EtherMeter EM-100, Инструкция по установке, эксплуатации и обслуживанию

Страница: 28 / 79

26
Debounce Filter:
In order to mitigate the adverse effects of contact bounce, user-adjustable de-bounce logic has
been implemented within the EtherMeter firmware.
The user may adjust the DBn parameter to increase or decrease the pulse sensitivity. DBn refers
to the minimum required quiet time enforced after the leading edge of a valid pulse has been
detected. DBn can be set to any value between 0 and 10000 milliseconds. When DBn is set to
ZERO, the debounce filter is disabled (factory default).
As an example, if DBn is set to 60, then any pulses which arrive before T
o
has expired will be
ignored.
PULSE METER
DEBOUNCE LOGIC
TIME
T
C
T
O
CONTACT
INPUT
CLOSED
OPEN
Figure 9C. Pulse Meter Debounce Logic Illustration
Batching Operations:
•
CNT1 can be reset to ZERO by writing a ‘1’ to Modbus Coil 9,
or by
writing a ‘1’ to Allen Bradley-compatible register B10:0/8.
•
CNT2 can be reset to ZERO by writing a ‘1’ to Modbus Coil 10,
or by writing a ‘1’ to Allen Bradley-compatible register B10:0/9.
Pulse Meter Notes:
•
Maximum pulse frequency: 2000 Hz (2000 Pulses Per Second).
•
Active Voltage and Current Pulses are not supported.
•
Each of the EtherMeter’s pulse-input channels contain an in5 VDC power supply
and a 900 Ohm pull-up resistor. Therefore, an external voltage source and pull-up resistor
circuit is not required.
•
The EtherMeter sources a maximum 0.5 milliamp through the contact circuit.
•
Totalization and Flow-Rate Calculations (UNITn, TBn, ROLLn, FCALCn, SAMPn, TOn
parameters) are handled identically for pulse-type meters as for encoder-type meters.
•
Factor-of-10 scaling (EXPn parameter) is handled identically for pulse-type meters and
encoder-type meters.
•
The pulse count(s) are stored to nonvolatile EEPROM every 8 minutes. Therefore, if the
power to the unit is cycled, then the loss of up to 8 minutes of pulses is possible. To reduce
the likelihood of lost pulses due to power outages, a battery backup power supply is
recommended.
•
When the user toggles DIP SWITCH 8 (SETUP/RUN Mode), then the current pulse
count(s) are immediately stored to EEPROM.